Friday, July 9, 2010

Nuclear Winter

MEANING

What is nuclear winter? it is first common question. Nuclear winter is a term that describes the predicted climatic effects of nuclear war. Severely cold weather and reduced sunlight for a period of months or years would be caused by detonating large numbers of nuclear weapons, especially over flammable targets such as cities, where large amounts of smoke and soot would be injected into the Earth's stratosphere. The term has also been applied to one of the after-effects of a comet or asteroid impact, also sometimes termed an impact winter, or of a super volcano eruption, known as a volcanic winter.Nuclear winter is a theoretical concept. In short, many scientists believe that a large scale nuclear war would change the global climate in great proportion. This is because such a war would likely catapult large amounts of soot and smoke (aerosol particles) into the Earth's stratosphere. Along with this, the ash and dust ( which could settle in the stratosphere for months or even years ) would likely travel by wind over a great distance to create a wall between the Earth and sun.

MECHANISMThe nuclear winter scenario predicts that the huge fires caused by Nuclear explosions (particularly from burning urban areas) would loft massive amounts of dark smoke and aerosol particles from the fires into the upper troposphere / stratosphere. At 10-15 kilometers (6-9 miles) above the Earth's surface, the absorption of sunlight would further heat the smoke, lifting it into the stratosphere where the smoke would persist for years, with no rain to wash it out. This would block out much of the sun's light from reaching the surface, causing surface temperatures to drop drastically.

CONSEQUENCESClimatic effectsA study presented at the annual meeting of the American Geophysical Union in December 2006 found that even a small-scale, regional nuclear war could produce as many direct fatalities as all of World War II and disrupt the global climate for a decade or more. In a regional nuclear conflict scenario where two opposing nations in the subtropics would each use 50 Hiroshima-sized nuclear weapons (about 15 kiloton each) on major populated centre, the researchers estimated fatalities from 2.6 million to 16.7 million per country. Also, as much as five million tons of soot would be released, which would produce a cooling of several degrees over large areas of North America and Eurasia, including most of the grain-growing regions. The cooling would last for years and could be "catastrophic" according to the researchers.Ozone depletionA 2008 study published in the Proceedings of the National Academy of Science found that a nuclear weapons exchange between Pakistan and India using their current arsenals could create a near- global ozone hole, triggering human health problems and wreaking environmental havoc for at least a decade. The computer-modeling study looked at a nuclear war between the two countries involving 50 Hiroshima-sized nuclear devices on each side, producing massive urban fires and lofting as much as five million metric tons of soot about 50 miles into the stratosphere. The soot would absorb enough solar radiation to heat surrounding gases, setting in motion a series of chemical reactions that would break down the stratospheric ozone layer protecting Earth from harmful ultraviolet radiation.Column ozone losses could exceed 20% globally, 25-45% at mid-latitudes, and 50-70% at northern high latitudes persisting for 5 years, with substantial losses continuing for 5 additional years. Column ozone amounts would remain near or below 220 Dobson units at all latitudes even after three years, constituting an extra-tropical “ozone hole”. Human health ailments like cataracts and skin cancer, as well as damage to plants, animals and ecosystems at mid-latitudes would likely rise sharply as ozone levels decreased and allowed more harmful UV light to reach Earth, according to the PNAS study. This study demonstrates that a small-scale, regional nuclear conflict is capable of triggering ozone losses even larger than losses that were predicted in the 1980s following a full-scale nuclear war. The missing piece back then was that the models at the time could not account for the rise of the smoke plume and consequent heating of the stratosphere.

CRITICISM OF NUCLEAR WINTER THEORY1980s criticismsThe original work by Sagan and others was criticized as a "myth" and "discredited theory" in the 1987 book Nuclear War Survival Skills, a civil defense manual by Cresson Kearny for the Oak Ridge National Laboratory. Kearny described nuclear winter mostly as a propaganda story, and said the maximum estimated temperature drop would be only about by 20 degrees Fahrenheit, and that this amount of cooling would last only a few days (though he did not address the question of whether a lesser amount of global cooling might linger for years, or whether there might be greater localized cooling in agricultural areas, as predicted by the 2007 study). He suggested that a global nuclear war would indeed result in millions of deaths from hunger, but primarily due to cessation of international food supplies, rather than due to climate changes. Kearny, who was not a climate scientist himself, based his conclusions almost entirely on the 1986 paper "Nuclear Winter Reappraised" by Starley Thompson and Stephen Schneider. However, a 1988 article by Brian Martin in Science and Public Policy states that although their paper concluded the effects would be less severe then originally thought, with the authors describing these effects as a "nuclear autumn", other statements by Thompson and Schneider show that they "resisted the interpretation that this means a rejection of the basic points made about nuclear winter". In addition, the authors of the 2007 study state that "because of the use of the term 'nuclear autumn' by Thompson and Schneider [1986], even though the authors made clear that the climatic consequences would be large, in policy circles the theory of nuclear winter is considered by some to have been exaggerated and disproved [e.g., Martin, 1988]. And in 2007 Schneider emphasized the danger of serious climate changes from a limited nuclear war of the kind analyzed in the 2006 study below, saying "The sun is much stronger in the tropics than it is in mid-latitudes. Therefore, a much more limited war [there] could have a much larger effect, because you are putting the smoke in the worst possible place.A 1986 article by Russell Seitz in The National Interest reported that prominent physicist Freeman Dyson said of the TTAPS study that it was "an absolutely atrocious piece of science, but I quite despair of setting the public record straight....Who wants to be accused of being in favor of nuclear war? However, the Brian Martin article mentioned above reported that Dyson had no memory of making this comment, and had said "I don't believe I ever said what Russell Seitz said I said, but I can't prove it. Seitz also mentioned that the Jan. 23, 1986 issue of Nature included a comment that nuclear winter research "has become notorious for its lack of scientific integrity." Steitz's assessment also introduced politics, stating that nuclear disarmament would lend an advantage to the Soviet Union, which harbored strong conventional forcesWill I Survive Nuclear Winter?Dealing with UV radiation -First order of business is the fact that ozone depletion could cause an abundance of UV radiation to seep through into our atmosphere. Thus, we would need to deal with this excess radiation, which in high amounts can cause skin cancer and eye problems ( especially to the cornea ). In fact, eye damage can actually occur without any pain or discomfort.In other words, without warning. Thus, here are some things to consider.1. Be covered from head to toe when under UV exposure. In other words, protect your skin!2. Wear a hat and stay in the shade as often as possible ( this is one thing that may be easier than it used to be if a nuclear winter were to occur! ).3. Use sunscreen with a high UV protection factor.4. Protect your eyes. Sunglasses can do this, as can lab safety glasses and / or goggles.5. Remember that children are more susceptible to UV radiation. Protect them without fail.Dealing with the cold -We really have no idea how cold it could get during a nuclear winter. Some, like the TTAPS crew, have proposed that it's going to get real cold. However, there is a growing feeling in the scientific community that these projections were way too strong. Regardless, with the already changing global climate, it's always better to be safe than sorry. Therefore, here are some considerations in dealing with a longstanding cold spell.1. Have emergency heating supplies on hand. - Remember that if a nuclear war were to occur, electric, gas, and oil might be off the table. Thus, it might be prudent to have a stove and a surplus of firewood at your home. Further, it couldn't hurt to have excess supplies of your preferred heating fuel stored away safely somewhere.2. Have appropriate clothing on hand. - Remember that clothing in frigid conditions should keep the body warm, protect the outer extremities, allow perspiration to disperse, allow free movement, and be comfortable. Thus, it is for the most part better to have several layers of clothing on rather than just one very thick layer. This is because the extra layers allow easier movement. Further, perspiration disperses more readily with several layers than with one.Beyond that, it would seem important to have boots, gloves, and sunglasses / goggles on hand. This may seem obvious to northerners, but remember that a nuclear winter could also reach those in warmer climates not accustomed to such weather.Then there's food -Remember that a longstanding winter would, of course, impact our ability to grow food ( also remember that in a nuclear winter, the amount of sunlight and precipitation would change ). Thus, food would no doubt become an issue even if the rest of our social structure remained intact.Therefore, finding ways to produce food on your own or within your social network would likely become vitally important. Initially, though, you might want to have a significant amount of non perishable food and water on hand. In fact, no matter what the emergency this could become needed ( tsunami, regular war, a terrorist attack of a different sort, etc. ).In other words, having a food supply on hand is a necessity in this day and age. Have one ready.

Last, remember that a nuclear winter indicates that a nuclear war has occurredSeems silly to mention, right? On the other hand, the point cannot be overstated. After all, the consequences of a nuclear conflict will go well beyond global climactic change and a nuclear winter. Depending on the size of the nuclear conflict, there could be widespread social disorder and chaos.